The present disclosure relates generally to a system for, and a method of, stitching barcode fragments of a barcode symbol to be read in an imaging-based presentation workstation of particular benefit when the barcode fragments have repetitive patterns of bars and spaces.
Point-of-transaction workstations employing imaging-based readers have been used in many venues, such as supermarkets, department stores and other kinds of retail settings, as well as libraries and parcel deliveries and other kinds of public settings, as well as factories, warehouses and other kinds of industrial settings, for many years. Such workstations were often configured either as stand-mounted scanners each having a presentation window; or as vertical slot scanners each having a generally vertically arranged, upright presentation window; or as flat-bed or horizontal slot scanners each having a generally horizontally arranged presentation window; or as bioptical, dual window scanners each having both a generally horizontal presentation window and a generally vertically arranged, upright presentation window. Such workstations were often operated to electro-optically read a plurality of symbol targets, such as one-dimensional symbols, particularly Universal Product Code (UPC) barcode symbols, truncated symbols, stacked symbols, and two-dimensional symbols, as well as non-symbol targets, such as driver's licenses, receipts, signatures, etc., the targets being associated with, or borne by, objects or products to be processed by, e.g., purchased at, the workstations.
A user, such as an operator or a customer, slid or swiped a product associated with, or bearing, the target in a moving direction across and past a respective presentation window in a swipe mode, or momentarily presented, and steadily momentarily held, the target associated with, or borne by, the product to an approximate central region of the respective presentation window in a presentation mode. The products could be moved relative to the respective window in various directions, for example, from right-to-left, or left-to-right, and/or in-and-out, or out-and-in, and/or high-to-low, or low-to-high, or any combination of such directions, or could be positioned either in contact with, or held at a working distance away from, either window during such movement or presentation. The choice depended on the type of the workstation, or on the user's preference, or on the layout of the venue, or on the type of the product and target. Return light returning from the target in the imaging-based reader was captured in one or more images, and then processed, and, when the target was a symbol, was decoded, and read, thereby identifying the product.
Although generally satisfactory for their intended purpose, one issue with such known presentation-type workstations involved the fact that not every image contained an entire barcode symbol and, hence, the symbol could not be read from a single image containing an incomplete symbol. During movement of a product past a window, each image captured by a single solid-state imager or camera positioned behind the window did not necessarily contain the entire symbol. In bioptical workstations, the images captured by multiple imagers or cameras positioned behind different windows likewise did not necessarily contain the entire symbol because, among other things, the product was moving, the imagers were looking in different directions, and the fields of view of the imagers were relatively narrow in practice.
In such circumstances, it was generally known to stitch barcode fragments of the symbol from the captured images. A barcode stitching method was disclosed in U.S. Pat. No. 5,821,519, and general string and sequence- and character-matching algorithms were described in a book entitled Algorithms on Strings, Trees, and Sequences: Computer Science and Computational Biology, by Dan Gusfield, published by the Press Syndicate of the University of Cambridge, Cambridge, England, 1997. Yet, as satisfactory as such stitching methods have been, they sometimes failed, especially when the barcode fragments had repetitive patterns of bars and spaces. Such repetitive patterns, particularly, in the center regions of the barcode fragments, made it impossible to stitch the barcode fragments together.
Accordingly, there is a need to improve the stitching of barcode fragments, especially when the barcode fragments have repetitive patterns of bars and spaces, and to enhance the overall reading performance of imaging-based presentation workstations.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and locations of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The system and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.